Abstract
Aim To evaluate dentinal microcrack formation on root canals instrumented, continuously in the body temperature, with XP-endo shaper (XPES) and ProTaper Universal (PTU), by means of microcomputed tomographic (micro-CT) analysis. Methodology. Nineteen mesial roots with two separate canals (Vertucci Type IV) of extracted mandibular molars were used in this study. The root canals (N = 38) were divided into 2 groups. Group 1 (n = 19): all MB canals were instrumented with XPES. Group 2 (n = 19): all ML canals were instrumented with PTU. All roots were scanned with micro-CT before and after instrumentation. Two precalibrated examiners evaluated the cross-sectional images of each sample with DataViewer program. The dentinal microcracks (complete and incomplete) were counted in each third of the root for the preinstrumentation and the postinstrumentation images. Wilcoxin signed-rank and Mann–Whitney U tests were used for statistical analysis at a significance level of P < 0.05. Results The number of microcracks increased significantly (P < 0.05) after instrumentation with XPES in the middle and cervical thirds. The number of microcracks increased significantly (P < 0.05) after instrumentation with PTU in the cervical third only. There was no significant difference between the groups in the cervical and apical thirds. In the middle third, the XPES induced more incomplete microcracks than PTU (P < 0.05). Conclusion Within the limitations of this study, there was no significant difference in the dentinal microcrack formation between XPES and PTU in the apical and cervical thirds of the root. However, XPES instrumentation induced more incomplete microcracks than PTU in the middle third of human roots.
Highlights
Disinfection of the root canal system is essential for successful root canal treatment [1]. e antibacterial effect of sodium hypochlorite cannot reach all bacteria in the dentinal tubules [2]. erefore, root canal mechanical enlargement is required to ensure the removal of infected dentine [3]
Previous studies reported that XPES instrumentation will cause no or few dentinal microcracks compared with other NiTi rotary systems [19,20,21]. None of these studies exposed the XPES files to body temperature during the instrumentation. erefore, in the present study, we aim to evaluate dentinal microcrack formation on root canals instrumented, continuously in the body temperature, with the XP-endo shaper (XPES) and ProTaper Universal (PTU), by means of microcomputed tomographic analysis
XPES and PTU groups, while the number of incomplete microcracks in the middle third increased significantly (P < 0.05) after instrumentation only in the XPES group (Figure 4). e apical third in all groups did not show any complete microcracks and only a few incomplete microcracks (Figure 5). ere was no significant increase in the number of microcracks in the apical third after instrumentation
Summary
Disinfection of the root canal system is essential for successful root canal treatment [1]. e antibacterial effect of sodium hypochlorite cannot reach all bacteria in the dentinal tubules [2]. erefore, root canal mechanical enlargement is required to ensure the removal of infected dentine [3]. Erefore, root canal mechanical enlargement is required to ensure the removal of infected dentine [3]. NiTi files might lead to dentinal defects and can induce microcracks in the dentinal walls of the root canal [5]. Microcomputed tomography (micro-CT) is the method of choice to evaluate and assess dentinal defects and microcracks induced by root canal instrumentation with different systems. Micro-CT is a nondestructive and noninvasive technique to obtain twodimensional and three-dimensional images of any tooth [7]. It enables scanning of the same sample for multiple tests without damage allowing each sample to be used as its own control [8]
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